Boulder Brain Coral

About

Boulder brain coral (Colpophyllia natans) is one of the most recognizable corals in the Caribbean and Gulf of Mexico, where it forms large hemispherical or encrusting colonies across shallow reef environments from the surface down to around 55 meters. The colony surface is defined by long, winding valleys separated by walls that are typically brown or grey, though the valleys themselves sometimes take on a muted green tone. Septa run in neat, finely toothed rows along the valley floors, and a shallow groove traces the tops of the walls between them. Like most large-polyp stony corals, this species keeps its tentacles retracted during the day and extends them only after dark to feed, so daytime observers see the textured skeleton rather than any soft tissue activity. In the aquarium, it is considered a manageable choice for reef keepers who are still building experience, as long as moderate lighting and moderate flow are maintained. Colonies can grow quite large given enough time, so this is one to place with some thought about long-term space. It poses no known threat to other reef inhabitants when given appropriate room.